Figure 1.

A summary of the evolution of mycorrhizal partners in orchids, emphasizing that they may have been recruited from fungi that were ancestrally endophytic (in orchids, fungi that are ectomycorrhizal on other plants can be endophytic or orchid-mycorrhizal, but for ease of reading, they are collectively qualified as ‘ectomycorrhizal’ fungi). (A) Hyphae and spores of Rhizophagus irregularis (courtesy Jelle van Creij, University of Wageningen). (B) Electron micrograph of an unknown rhizoctonia peloton in a Dactylorhiza majalis orchid mycorrhiza. (C) Fruiting bodies of ectomycorrhizal Russula cyanoxantha. (D) Fruiting bodies of litter-decaying Mycena spp.